An electronic device may produce and radiate energy that can disrupt the operation of neighboring electronic devices. This effect is referred to as radio frequency interference (RFI).
Electronic devices are commonly enclosed in a housing or enclosure to prevent energy from radiating to neighboring devices. Typically, the enclosure has one or more openings or ports. The openings can be used to gain access to internal components for installation and maintenance, for example. The openings can also be used to connect accessory devices or add expansion modules, for example. The openings are covered to prevent the release of energy that might disrupt neighboring devices.
There are many different types of covers used in the prior art, but each is problematic in some manner. One type of cover is held in place using one or more screws. A disadvantage of this design is that a relatively large amount of additional space is needed on the surface of the enclosure in order to provide a location to insert the screw(s). In other words, the footprint of the cover extends well beyond the footprint of the opening because space is needed adjacent to the opening to accept the screw(s) that hold the cover in place. Another disadvantage is that a tool such as a screwdriver is needed to install and remove the screw(s). Although larger screws that can be installed by hand may instead be used, these larger screws are relatively expensive and further enlarge the footprint of the cover.
Another type of cover snaps in place to close the opening. A problem with the snap-in cover design is that it may not be tight enough to prevent energy from escaping. Another problem with this design is that it is usable only for a limited number of cycles before wearing out due to fatigue. Furthermore, the cover may pop out of place when the electronic device is being handled or moved or simply due to wear. If the cover is situated out of sight (e.g., on the rear of the enclosure), its absence may not be noticed, allowing energy to escape through the opening and disrupt neighboring devices.
A cover similar in design to the snap-in cover is a molded conductive elastomer cover. However, this design shares the disadvantages of the snap-in cover with the added disadvantage that a tool may be required for removal.
In general, prior art cover designs have one or more of the following disadvantages: they have a footprint that is significantly larger than the footprint of the opening, limiting the density of ports on the enclosure; they require tools for installation and removal; they do not adequately prevent energy from leaking out of the enclosure; they do not stay in place, in particular if the enclosure is subject to shock loads or vibrations; they need to be manufactured to precise manufacturing tolerances; and/or they are usable only for a limited number of cycles before wearing out.
Accordingly, a cover design that addresses these problems would be of value. Embodiments of the present invention provide a cover design that addresses all of these problems.